George Walford: Global Warming

The suspicion that average temperatures over the planet may be rising, or set to rise in future, with disastrous consequences to follow, has become an ideological battleground. On the one hand the eidodynamics, emphasising the danger and calling for restraints to avoid or at least minimise it. On the other, the eidostatics, professing the best intentions while continuing to develop the industry that has produced the danger (if there is one).

Is the average temperature of the planet in fact rising or about to start doing so? It sounds like a factual issue, one for science to resolve, but the experts disagree and one can see why. The average temperature of the earth is an extremely difficult, perhaps impossible, thing to measure directly. Any accurate measurement has to be made at one location in space and time; a difference of yards or minutes not uncommonly produces a fluctuation vastly exceeding the change over some very small number of degrees predicted for global warming over the next century. In reaching any figure for the planet the hypotheses, assumptions and theories that have to be adopted come close to swamping the kernel of fact, and those adopted vary with the ideology of the assumer. In the letter appearing elsewhere in this issue Trevor Blake draws attention to the work of Iben Browning on some of these complications, suggesting that any rise may be no more than a return to normal for the planet after a long coldish period. Let us hope it will not be a return to normal in all respects; for most of its life the planet has been without humanity.